Histogenesis of the stomach of the pre-hatching quail: a light microscopic study

The current study conducted a careful description of the histological events during the embryonic development of quail stomach. Daily histological specimens from the quail stomach from day 4 to day 17 post incubation were examined by light microscopy. The primitive gut tube of the embryonic quail appeared at day 4 post incubation. The gut tube consisted of an endodermal epithelium of pseudostratified type, surrounded by splanchnic mesenchyme. The prospective glandular epithelium invaginated at day 5 in the proventriculus and gradually developed to prospective proventricular glands. The muscular coat became distinguished at day 7 and day 8 in the proventriculus and gizzard, respectively. Transformation into simple columnar epithelium occurred in both proventriculus and the gizzard at day 12. The gizzard epithelium gave rise to tubular invaginations also at day 12. Canalization of the gizzard tubular glands was recognized at day 14. By day 15, the proventricular surface epithelium invaginated in a concentric manner around a central cavity to form immature secretory units that contained inactive oxyntico-peptic cells. The mucosal folding in the gizzard appeared at day 15 to form plicae and sulci. The wall of the proventriculus and gizzard at day 17 acquired histological features of post-hatching birds.